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William "Sandy" Schenck lead a field trip through the Delaware Piedmont for the A.I. duPont High School Earth Science Class. The trip made use of the Wilmington-Western Railroad and everyone rode the railroad's "Doodle Bug." Activities included up close examinations of rock and mineral features and even "Panning for Garnets" at Brandywine Springs Park.

The Delaware Piedmont is but a small part of the Appalachian Mountain system that extends from Georgia to Newfoundland. This mountain system is the result of tectonic activity that took place during the Paleozoic era, between 543 and 245 million years ago. Since that time, the mountains have been continuously eroding, and their deep roots slowly rising in compensation as the overlying rocks are removed. It is surprising to find that although the Delaware Piedmont has passed through the whole series of tectonic events that formed the Appalachians, the mineralogy and structures preserved in Delaware were formed by the early event that occurred between 470 and 440 million years ago, called the Taconic orogeny.

This report accompanies a new map that revises the original bedrock geologic maps of the Delaware Piedmont compiled by Woodruff and Thompson and published by the Delaware Geological Survey (DGS) in 1972 and 1975. Combined detailed mapping, petrography, geochemistry, and U-Pb geochronology have allowed us to redefine two rock units and formally recognize eleven new units. A section of the Pennsylvania Piedmont is included on the new map to show the entire extent of the Mill Creek Nappe and the Arden Plutonic Supersuite.

GeoAdventures are designed to allow the reader to learn about a particular geologic point of interest in Delaware’s Piedmont province and then take a short field trip to that area. Want to know more about the Wilmington blue rock or Brandywine blue granite? Take the Wilmington Blue Rock GeoAdventure and go see just what the blue rock looks like.